enewable energy has reached an important milestone. The World Economic Forum (WEF) has determined that in many parts of the world, solar energy is now the same price or even cheaper than fossil fuels for the first time.

In a handbook released this month, the WEF observed how the price of renewable technologies, particularly solar, has declined to unprecedented lows.

While the average global LCOE [levelized cost of electricity] for coal and natural gas is around $100 per megawatt-hour, the price for solar has plummeted from $600 a decade ago to $300 only five years later, and now close to or below $100 for utility-scale photovoltaic. For wind, the LCOE is around $50.

According to the WEF, more than 30 countries have already reached grid parity—even without subsidies. (“Grid parity” is the point when an alternative energy source, say solar, can generate power at a LCOE that’s equal or even less than the price of traditional grid power.)

“It is relevant to note that the mentioned evolution, market share gain and continued potential for renewable energy do not hinge on a subsidy advantage,” the report added. “In fact, according to [International Energy Agency], fossil-fuel consumption has received $493 billion in subsidies in 2014, more than four times the value of subsidies to renewable energy.”

The WEF highlighted how the unsubsidized LCOE for utility-scale solar photovoltaic—which was not competitive even five years ago—has declined at a 20 percent compounded annual rate, “making it not only viable but also more attractive than coal in a wide range of countries.”

Countries that have already reached grid parity include Chile, Mexico, Brazil and Australia with many more countries also on the same track. The WEF projects that two thirds of the world will reach grid parity in the next couple of years, and by 2020, solar photovoltaic energy is projected to have a lower LCOE than coal or natural gas-fired generation throughout the world.

“Renewable energy has reached a tipping point,” Michael Drexler, who leads infrastructure and development investing at the WEF, told Quartz. “It is not only a commercially viable option, but an outright compelling investment opportunity with long-term, stable, inflation-protected returns.”

The report follows a recent analysis from the IEA which revealed that total clean power capacity increased by 153 gigawatts, overtaking coal for the first time. To illustrate, about 500,000 solar panels installed were installed around the world every day.

The hybrid photovoltaic cell has a claimed efficiency of 21.7 percent, already better than the 10 to 20 percent of standard polycrystalline silicon solar cells currently in use(Credit: Onur Ergen/UC Berkeley)

http://newatlas.com/perovskite-solar-pv-grahene-aerogel/46346/

Scientists working at the University of California, Berkeley (UC Berkeley), and Lawrence Berkeley National Laboratory (LBNL) have created a hybrid photovoltaic cell from multiple layers of different perovskite materials that has a claimed a peak efficiency of 26 percent. It’s said that the cell can easily be sprayed onto flexible surfaces to make bendable, high-efficiency solar panels.

A hybrid organic-inorganic conglomerate, perovskite is used in solar cells to capture light in a similar way to common silicon-based solar cells by converting incoming photon energy into electrical current. Unlike rigid silicon semiconductor materials that require a great deal of expensive processing and manipulation to turn them into solar cells, however, perovskite photovoltaic devices are said to be cheaper and easier to make, in addition to being much more flexible.

The new UC berkeley/LBNL device is also very efficient thanks to a sandwich of two types of perovskite separated by a single-atom thick layer of hexagonal boron nitride (sometimes referred to as “White graphene”) with each perovskite slice designed as a graded bandgap layer (put simply, of low resistance and high gain) able to absorb different wavelengths of light. This combination effectively creates a photovoltaic cell able to collect and convert energy across most of the light spectrum.

“This is realizing a graded bandgap solar cell in a relatively easy-to-control and easy-to-manipulate system,” said Alex Zettl, a UC Berkeley professor of physics. “The nice thing about this is that it combines two very valuable features – the graded bandgap, a known approach, with perovskite, a relatively new but known material with surprisingly high efficiencies – to get the best of both worlds.”

In detail, the perovskite materials are made of methyl and ammonia organic molecules, with one containing tin and iodine and designed to absorb infrared light in the 1 electron volt (eV) range, and the other consisting of lead and iodine doped with bromine that absorbs amber photons of energy at 2 eV. A single-atom layer of boron nitride then provides an intermediate junction to operate in tandem and create electricity from across the light band.

This entire layered combination is then stabilized mechanically by placing it on top of a lightweight graphene aerogel to enhance the formation of fine-grained perovskite crystals as well as serve as a moisture barrier to stop the water-soluble perovskites falling to pieces. Lastly, the whole conglomeration has a gold electrode attached to the underside, along with a gallium nitride layer added to the uppermost part that gathers up the electrons generated when the cell is exposed to light. And all this with an active layer just 400 nanometers thick.

“Our architecture is a bit like building a quality automobile roadway,” said Zettl. “The graphene aerogel acts like the firm, crushed rock bottom layer or foundation, the two perovskite layers are like finer gravel and sand layers deposited on top of that, with the hexagonal boron nitride layer acting like a thin-sheet membrane between the gravel and sand that keeps the sand from diffusing into or mixing too much with the finer gravel. The gallium nitride layer serves as the top asphalt layer.”

With a standard operating efficiency of around 21.7 percent, the new wide spectrum hybrid perovskite cell is already better than the 10 to 20 percent efficiency of standard polycrystalline silicon solar cells currently in use in a host of commercial equipment and household solar systems. Even the best silicon solar cells made today are lucky to get over 25 percent efficiency, and are complex and expensive to produce.

“We have set the record now for different parameters of perovskite solar cells, including the efficiency,” said Zettl. “The efficiency is higher than any other perovskite cell – 21.7 percent – which is a phenomenal number, considering we are at the beginning of optimizing this.”

“Our theoretical efficiency calculations should be much, much higher and easier to reach than for single-bandgap solar cells because we can maximize coverage of the solar spectrum,” added Onur Ergen, a UC Berkeley physics graduate student.

The possibility exists to add further layers of hexagonal boron nitride-separated perovskite to help increase efficiencies even further, but the researchers believe that the thin new material may be efficient enough, and certainly sufficient for producing acceptable efficiencies for commercial production.

“People have had this idea of easy-to-make, roll-to-roll photovoltaics, where you pull plastic off a roll, spray on the solar material, and roll it back up,” said Zettl. “With this new material, we are in the regime of roll-to-roll mass production; it’s really almost like spray painting.”

Hong Kong is facing serious air pollution, which can cause irreversible damage to our society. To cope with the problem, some may suggest the adoption of larger-scale usage of solar power. However, I don’t think that it is feasible to widely use solar power in Hong Kong.

Firstly, from the economic perspective, I think it is very difficult to instal a lot of solar panels in our city. The cost of solar power is very high, even higher than that for conventional fossil fuels (for example, coal and natural gas). That is because we have to buy not just one, but a large number of solar panels. Also, we have to rent a big flat for enough area to place the solar panels, and it will be very expensive to do so.

Moreover, we have to purchase new generating units, as we cannot possibly use the old units for solar energy. Despite its unbelievably high cost, the efficiency of converting solar energy into electricity is very low.

Secondly, considering Hong Kong’s geographical structure, I think it is difficult to use solar power widely here. Solar panels require large open areas for instalments, while Hong Kong is fairly mountainous. So it would be difficult to find open and flat spaces to place solar panels in a place this hilly.

Moreover, Hong Kong’s high population density and scarce land already makes it difficult to find enough space for living. If Hong Kong had enough space, it should be used to build public housing, which is a much more serious problem. We cannot possibly try to solve one problem if it gives rise to a worse one.

If citizens oppose the promotion of solar energy, it will surely not be feasible, and it is very unlikely that they, especially the underprivileged, will support such an idea when using solar power would mean higher electricity bills for them.

All in all, I do not think it is practical to have wide use of solar power in Hong Kong. We should be looking at other forms of renewable energy that would have a much greater chance of success.

The latest draft version of the TTIP agreement could sabotage European efforts to save energy and switch to clean power, according to MEPs.

A 14th round of the troubled negotiations on a Transatlantic Trade and Investment Partnership (TTIP) free trade deal between the EU and US is due to begin on Monday in Brussels.

A leak obtained by the Guardian shows that the EU will propose a rollback of mandatory energy savings measures, and major obstacles to any future pricing schemes designed to encourage the uptake of renewable energies.

Environmental protections against fossil fuel extraction, logging and mining in the developing world would also come under pressure from articles in the proposed energy chapter.

Paul de Clerck, a spokesman for Friends of the Earth Europe, said the leaked document: “is in complete contradiction with Europe’s commitments to tackle climate change. It will flood the EU market with inefficient appliances, and consumers and the climate will foot the bill. The proposal will also discourage measures to promote renewable electricity production from wind and solar.”

The European commission says that the free trade deal is intended to: “promote renewable energy and energy efficiency – areas that are crucial in terms of sustainability”.

The bloc has also promised that any agreement would support its climate targets. In the period to 2020, these are binding for clean power and partly binding for energy efficiency, in the home appliance and building standards sectors.

But the draft chapter obliges the two trade blocs to: “foster industry self-regulation of energy efficiency requirements for goods where such self-regulation is likely to deliver the policy objectives faster or in a less costly manner than mandatory requirements”.

Campaigners fear that this could tip the balance in future policy debates and setback efforts to tackle climate change.

Jack Hunter, a spokesman for the European Environmental Bureau said: “Legally-binding energy standards have done wonders to lower energy bills for homes and offices, so much so that energy use has dropped even as the British economy has grown and appliances have become more power-hungry.

“Voluntary agreements have a place, but are generally ‘business as usual’ and no substitute for the real thing. If they became the norm, it would seriously harm our fight against climate change.”

Another passage in the draft text mandates that operators of energy networks grant access to gas and electricity “on commercial terms that are reasonable, transparent and non-discriminatory, including as between types of energy”.

This could create an avenue for preventing the imposition of feed-in tariffs and other support schemes to encourage the uptake of clean energy, according to lawmakers in Brussels.

The Green MEP Claude Turmes said: “These proposals are completely unacceptable. They would sabotage EU legislators’ ability to privilege renewables and energy efficiency over unsustainable fossil fuels. This is an attempt to undermine democracy in Europe.”

The environmental law consultancy, ClientEarth, was concerned that the new proposal effectively derogated responsibility for urgent climate change actions agreed at COP21 to the business sector.

“Industry is not the right entity to lead the fight against climate change,” said ClientEarth’s lawyer, Laurens Ankersmit. “It is madness for the EU and the US to rely on it in this way.”

The energy chapter negotiations began as part of an EU push for unlimited access to exports of the US’s relatively cheap liquefied natural gas, much of it derived from shale.

The EU is committed to a reduction in greenhouse gas emissions of at least 80% by 2050, as measured against 1990 levels – and pledged a 40% CO2 cut by 2030 at the Paris climate conference, last December.

But the new text says that: “the Parties must agree on a legally binding commitment to eliminate all existing restrictions on the export of natural gas in trade between them as of the date of entry into force of the Agreement”.

Other countries wanting to trade with the EU or US would also find themselves up against requirements that they remove trade barriers.

China is helping Pakistan build the largest solar farm in the world. When complete in 2017, the solar farm could have 5.2 million photovoltaic cells, producing as much as 1,000 MW of electricity, enough to power about 320,000 households.

San Francisco has this week passed landmark legislation requiring all new buildings under 10 storeys in height to be fitted with rooftop solar panels.

The city’s San Francisco Board of Supervisors unanimously passed the new rule on Tuesday, making the metropolis the largest in the US to mandate solar installations on new properties.

Smaller Californian cities such as Lancaster and Sebastopol already have similar laws in place, but San Francisco is the first large city to adopt the new standard.

From January 2017 all new buildings in the city with 10 floors or fewer must have either solar PV or solar thermal panels installed. The measure builds on existing Californian state law which requires all new buildings to have at least 15% of their roof space exposed to sunshine, in order to allow for future solar panel use.

Supervisor Scott Wiener, who introduced the legislation, said the new measure would put San Francisco at the forefront of the US fight against climate change.

“In a dense, urban environment, we need to be smart and efficient about how we maximise the use of our space to achieve goals such as promoting renewable energy and improving our environment,” he said in a statement.

Wiener is also working on legislation that will allow “living roofs” – which provide low-cost insulation, minimise storm flooding issues and provide new wildlife habitats – to also be eligible to meet the new requirements. The proposals are expected to be introduced in the coming weeks.

“This legislation will activate our roofs, which are an under-utilised urban resource, to make our city more sustainable and our air cleaner,” Wiener added.

San Francisco has a target to source 100% of its electricity from renewable sources by 2020 and has emerged as one of the US’s leading clean tech hubs with a raft of Silicon Valley investors and entrepreneurs backing a host of green technology start-ups in the region

Engineers from Michigan State University (MSU) are designing transparent solar panels that could be retrofit to existing glass-covered buildings to generate electric power.

Traditional opaque solar panels such as silicon soak up much of the sun’s light, including visible light, and convert it to energy. A transparent panel allows visible light to shine through and making light that is invisible to the human eye—such as ultraviolet and infrared—do the work.

By making the solar panels transparent, MSU materials scientist and chemical engineer Richard Lunt and his team are creating the potential for them to cover existing windows.

However, making the panels clear is a challenge. So the team came up with ways to layer patterns onto the cell in a way that makes them uniformly transparent. The transparent solar cell under development incorporates thin coatings of organic and inorganic nanostructure materials that selectively harvest the parts of the solar radiation spectrum that are not visible to the eye.

“We actually used a variety of different stencils to pattern our devices,” Lunt says. Each active material has its own pattern. After every layer, the researchers put down a new stencil and in this way build complex structures, he adds.

Team member Margaret Young is testing whether the same process can be used on thin plastic.

“This is much lighter and much more flexible, so instead of rebuilding windows, we could just put this over an existing window,” she says.

Lunt says that he expects that in the next 20 years, this type of technology will be deployed extensively—turning cities and landscapes into solar harvesting systems, surfaces and solar farms without the aesthetic issues that today’s opaque solar panels create.

Germany’s share of renewable energy input into the gross national energy requirement is set to hit the 33% mark for 2015. Some 193 billion kWh will come from solar, wind, and other renewable sources for 2015, around a 20% increase on the previous year, according to the estimates from the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) and the German Association of Energy and Water Industries (BDEW).

The most significant increases have been in photovoltaic and wind energy: Wind outlets produced 47% more power up to Oct. 31 than in the same period last year, while photovoltaic sources had already beaten their total production for 2014 in the first 10 months of 2015, despite only modest increases in installations.

“Even if we don’t hit 33%, the overall increase in Germany’s renewable energy share is terrific news,” said Thomas Grigoleit, director of Energy, Environment and Resources at Germany Trade and Invest.

“Not only does it show how important this aspect is in terms of Germany’s Energiewende and climate change targets, it confirms Germany’s pioneering position in the industry. Germany is able not only to install this capacity but integrate it effectively into the grid.”

October 12 (SeeNews) – Researchers at Uppsala University, Sweden, have discovered that some old dye-sensitized solar cells can perform better when they have dried-out, and are conducting further research in the work of such “zombie” solar cells.

In the so-called Graetzel cell, an electrically conductive liquid facilitates a flow of electrons. When this liquid was gone, a solid hole conducting structure was created, continuing to transport positive charge, as revealed by Gerrit Boschloo’s group at the Department of Chemistry-Angstroem Laboratory.

In certain cases, the dried-out solar cells worked better than before. Boschloo said specific cells had hit 8% power conversion efficiency, a record for dye-sensitized solar cells with a solid hole conductor.

“Several companies have said that if it would only seal properly, they’d invest in liquid-based solar cells. If we would be able to seal these ‘zombie cells’ so that they would last for years, it would be very interesting,” Boschloo commented.

The research group is collaborating with two chemistry groups at The Royal Institute of Technology (KTH) and experts in the field of industrial manufacturing from Swerea IVF. The researchers have filed a patent application for the “zombie solar cell” through their own company Dyenamo.

Behold, the Solar Sunflower! Here they are trying a bunch of different reflector materials, which is why the segments all look slightly different. Some of the reflectors are covered up to protect them from the elements, or to stop them from frying a nearby engineer.

High on a hill was a lonely sunflower. Not a normal sunflower, mind you; that would hardly be very notable. This sunflower is a solar sunflower that combines both photovoltaic solar power and concentrated solar thermal power in one neat, aesthetic package that has a massive total efficiency of around 80 percent.

The Solar Sunflower, a Swiss invention developed by Airlight Energy, Dsolar (a subsidiary of Airlight), and IBM Research in Zurich, uses something called HCPVT to generate electricity and hot water from solar power. HCPVT is a clumsy acronym that stands for “highly efficient concentrated photovoltaic/thermal.” In short, it has reflectors that concentrate the sun—”to about 5,000 suns,” Gianluca Ambrosetti, Airlight’s head of research told me—and then some highly efficient photovoltaic cells that are capable of converting that concentrated solar energy into electricity, without melting in the process. Airlight/Dsolar are behind the Sunflower’s reflectors and superstructure, and the photovoltaics are provided by IBM.

The two constituent technologies of the Solar Sunflower—concentrated solar thermal power and photovoltaic solar power—are both very well known and understood at this point, and not at all exciting. What’s special about the Sunflower, however, is that it combines both of the technologies together in a novel fashion to attain much higher total efficiency. Bear with me, as this will take a little bit of explaining.

The reflectors are simply slightly curved, mirrored panels. Airlight has tried a variety of different reflector materials, from glass to mylar, but it looks like they have finally settled on aluminium foil, which isn’t prohibitively expensive and has very high reflectance. Aluminium foil does need additional material to protect it from the elements, though, as it’s very flimsy. The Sunflower has six “petals,” each consisting of six reflectors. At the focal point of the 36 reflectors there are six collectors, one for each block of six reflectors.

The collectors are where most of the magic occurs. To begin with, each collector has an array of gallium-arsenide (GaAs) photovoltaic cells. GaAs is much more efficient at converting sunlight into electricity (38 percent in this case, versus about 20 percent for silicon), but it’s much, much more expensive. With the Sunflower, though, space is at a premium: the sunlight is only focused on a very small region, so you need to use the absolute best cells available. The GaAs array in each collector only measures a few square centimetres, and yet it can produce about 2 kilowatts of electricity (so, one Sunflower generates about 12kW of electricity in total).

Photovoltaic cells, like most semiconductors, become less efficient as they get hotter. The GaAs cells used by the Sunflower have a max operating temperature of around 105°C. The problem is, when you focus the power of 5,000 suns on a single point, things get a lot hotter than 105°C. During one test, Airlight told me that they used the reflectors to melt a hole in a lump of iron (which has a melting point of 1538°C); during another test, the reflectors were misaligned and “we had molten aluminium dripping everywhere.”

How then do you stop your collectors turning into very expensive puddles of molten metal?

What a complete Solar Sunflower installation would look like, providing heat and electricity to a nearby house/office/factory.

Cooling with hot water? Cool.

The answer is a very clever cooling system, borrowed from one of IBM’s specialities: supercomputers. In high-performance computing (HPC) installations, heat is one of the limiting factors on how much processing power you can squeeze into a given volume. Computer chips are tiny; you could physically cram hundreds of them into a 1U server chassis, if you so wished. Cooling them, though, is another matter entirely. You can use fancy heat pipes, or perhaps immerse the whole thing in liquid, but it only gets you so far.

Over the last few years, IBM has been working on advanced methods of liquid cooling, primarily to boost compute density, but also to reduce the amount of waste heat (getting rid of it increases efficiency and reduces costs). In a conventional liquid cooling setup, there’s a water block (a lump of metal with some channels for liquid to flow through), a pump, and a radiator. The liquid is usually water, but it could be something else, like Fluorinert or mineral oil. Heat is transferred from the computer chip to the liquid, and then carried to the radiator and released into the atmosphere. This is inefficient for two reasons: there’s a limit to how much heat can be “picked up” as the fluid passes through the block; and the heat being radiated into the atmosphere is wasted.

IBM solves both of these problems with its hot-water cooling technology. First, instead of the hot water passing through a radiator and venting the thermal energy out into the atmosphere, the hot water is simply used as hot water: to heat homes, or to drive industrial processes, such as desalination, pasteurisation, drying, cooking, etc. IBM already has an example of this in Aquasar, a supercomputer at ETH in Zurich, where the hot water is used to heat university buildings.

Second, to increase heat transfer from the chip to the water, IBM has replaced the dumb ol’ water block with a piece of silicon with microfluidic channels. This piece of silicon, which is then stuck to the back of the computer chip like a tiny water block, has thousands of tiny channels that bring the water to within just a few microns of those pesky heat-generating transistors. This massively increases the amount of heat that can be dissipated, plus all of those discrete channels do a lot better job of dealing with chip hot spots (small regions that are more active than others) than the handful of giant channels in a conventional water block.

Okay, Seb, get back to the sunflowers…

The Solar Sunflower uses this exact same cooling technology—but instead of computer chips, those microfluidic slices of silicon are stuck to the backside of those gallium-arsenide photovoltaic cells. The cooling system ensures that the GaAs efficiently converts photons into electrons, while at the same time whisking away the thermal energy of 5,000 suns. It’s pretty cool, to be honest. Or hot. Or something.

The end result is a device that produces about 12kW of electricity, along with 21kW of thermal energy (with water temperatures up to 90°C). Neither Airlight or IBM would reveal the exact pricing of a single Sunflower, but the fully installed cost will likely be in the tens-of-thousands-of-pounds range—and that’s just the first caveat of many.

For a start, concentrated solar power only works with direct sunlight: the reflectors need to be pointed directly at the sun, and anything less than totally clear skies will significantly reduce power generation. The Sunflower has some control software that automatically tracks the sun, but IBM gave me a distinct “no comment” when I petulantly probed them about their ability to rid the world of clouds.

Second, there’s the lack of energy density: the Sunflower is very efficient, but it still only produces 12kW of electricity. That’s enough to power maybe three or four homes—during the few hours of the day that the sun is visible, anyway. You would need a large field of these things to power a town—and again, you’d need some kind of energy storage solution to get through the evenings, winters, and periods of inclementousness.

Perhaps the largest problem, though, is cost. When Airlight and IBM started work on the Solar Sunflower, the cost of bog-standard silicon solar cells was about £1 ($1.60) per watt. Over the last few years, as China has ramped up production, the cost has dropped precipitously to about 25p (40 cents) per watt—plus the efficiency of silicon PVs has improved, too. With its GaAs cells, fancy plumbing, control systems and motors, the giant lump of concrete, and the time it takes to construct the whole thing, the Solar Sunflower simply can’t compete with hectares of boring-ass silicon photovoltaics.

What a completed Solar Sunflower installation might look like in the future. Maybe. (This is a computer render.)